Answer choice A

@shafieiava, Let's look at (A). (A) says, "in spite of the difficulties encountered, at one time or another people have tried to domesticate each wild large mammal species" Since this is a strengthen with a necessary premise question, we can use the negation test. Negating (A), we have There is at least one wild large mammal species that people haven't yet tried to domesticate. (A)'s negation doesn't wreck the argument because the argument's premises state that people have attempted to domesticate all of the species that are worth it. Thus, we don't have to assume that they have tried to domesticate every single large mammal. This is why (A) isn't a necessary premise. Does this make sense? Let us know if you have any other questions!

So, I picked the correct answer choice for this question; however, doing the Blind Review, I was also tempted to choose "D". What makes "D" wrong? I was hoping to read the explanation; however, explanations weren't given for this section.

Broadly, I think D is wrong because the author could agree or disagree with it. The author could think that the more useful an animal is the easier it is to domesticate it, or she could completely disagree with it. These are two independent causal explanations to her. We don't need to have a relationship between ease and use in order for the argument to work.